The present invention relates to filtering elements, and especially to a diatomaceous earth caking filter element for swimming pools, and the like.
In the past, a great variety of swimming pool and other liquid filters have been provided for filtering liquids therethrough. Swimming pool and water filters typically work on either pressure where a pump drives the water through the filtering element or on suction, where a pump sucks the water through the filtering element.
Typical prior art patents include sand filters in which water is drawn through pressure or suction through a pressurized container filled with sand for filtering the water with the sand. The sand filter can then be back-washed to remove accumulated filtered solids and on occasion must have the sand removed and replaced in the filter. Another common filtering technique for swimming pools uses a papaer filtering element similar to industrial filtering elements in which a paper or synthetic material is formed into a filter which is typically formed into a corrugated tube to provide a larger surface area. Liquid is drawn through the paper filtering element for filtering the liquid. Paper filtering elements are typically replaced on a periodic basis and the old filtering unit is thrown away when it becomes clogged with filtered solids. One of the more common filtering units uses diatomaceous earth, however, having a high capacity for filtering liquids passing therethrough. Diatomaceous earth, however, is commonly caked on a screen and the liquid filtered through the caked screen for filtering solids from the liquid. Diatomaceous earth can be added to the filter on a regular basis and the filter can be back-washed for removing old diatomaceous earth. In filters of this type, the diatomaceous earth is deposited on the filter medium, consisting of a very fine mesh screen placed in the liquid for preventing the passage of the diatomaceous particles contained in a slurry of liquid including the diatomaceous particles and removes all foreign matter in suspension so that the liquid finally discharged from the filter is clear and unpolluted by solid materials such as fine solids in the liquid.
One prior art Patent to Klein, U.S. Pat. No.: 2,426,618 shows a diatomaceous earth filter of the same type as employed in the present invention, and includes corrugated metal connected between two pipes with one corrugated end acting as a manifold and having a plurality of hollow nipples extending therefrom. In this type of filtering element, all of the liquid is drawn to one end of the filter element into the manifold and out the suction pipe connected to the manifold. This tends to reduce the filtering as all of the filtered liquid tends to be pulled through the filtering screen towards one end and tends to have the diatomaceous earth caking more towards that end rather than a more uniform distribution of the liquid passing through the screen in a more evenly distributed manner as in the present invention.
Other prior art filters may be seen in the Hoskins Patent, U.S. Pat. No.: 3,481,479 for a Vacuum Filter, and in the Conrad Patent, U.S. Pat. No.: 3,471,022 for a swimming pool filter having rings stacked in spaced alignment with a filter envelope enclosing the stacked rings. The stacked rings are secured together and fastened to a manifold communicating with the interior of the envelope. In U.S. Pat. No.: 4,411,782 to Auld, a means for securing a screen over a filter is provided, and allows liquid to be drawn from both ends of the filter screen.